1. Field of the Invention
The present invention relates to joint connectors used for, for example, branching a wire harness (electric wires) wired in an automobile, and particularly to a joint connector that can achieve cost reduction and exhibit excellent workability in connecting electric wires.
2. Description of the Prior Art
Hereinbelow, a first prior art and its problems to be solved are discussed.
In recent years, electrical components incorporated in, for example, automobiles have increasingly been diversified. This has created the necessity of branching wire harnesses in complex manners, and accordingly, there has been a greater use of joint connectors.
Here, an example of prior-art joint connectors is described. One example of the terminal in a first prior-art joint connector of this kind has a male terminal portion and a female terminal portion provided in one piece of terminal and an electric wire press-fit portion partially provided so as to be connected with an electric wire by press-fitting. In a stacking direction of one-stage parallel-line-shaped connectors, that is, in a vertical direction, the male terminal portions are extended from a housing so as to straddle the housings to make connection. By stacking the press-fit joint connectors, the male terminal portions are inserted into female terminal portions of another joint connector terminal to be connected, which has the same shape. In addition, a terminal-linking portion is used to make connection in the terminals' juxtaposed direction (lateral direction) within a single one-stage parallel-line-shaped connector using terminal-linking portions.
This structure is described with reference to the drawings. As shown in FIG. 1, joint connector terminals 110 have male terminal portions 111 protruding upwardly, female terminal portions (not shown), and electric wire press-fit portions 112. By stacking one-stage parallel-line-shaped press-fit joint connectors 100 in which a plurality of joint connector terminals 110 are juxtaposed, a lower stage male terminal portion 111 is fitted and connected with an upper stage female terminal portion, and electrical connection is achieved between the upper and lower one-stage parallel-line-shaped press-fit joint connector terminals.
The continuity in the terminal's lateral direction (terminal's juxtaposed direction) is made through a terminal-linking portion, which is not shown in the figure, so that electrical connection is made in the one-stage parallel-line-shaped press-fit joint connector (see, for example, Japanese Unexamined Patent Publication No. 2001-291567).
In another prior-art joint connector, which is a second prior-art joint connector, a terminal 210 itself has, as shown in FIGS. 2 and 3, a female terminal portion 211 (see FIG. 3) and a male terminal portion 212, as the above-described first prior-art joint connector 100. Specifically, the female terminal portion 211 is formed at a front portion of one terminal, and a portion thereof that extends further forward from the female terminal portion 211 is bent back to form the male terminal portion (joint portion) 212. In addition, a plurality of the terminals 210 are arranged in a juxtaposed condition, these terminals 210 are formed in a shape such that they are linked through a carrier 201 in a lateral direction, and the male terminal portions 212 formed to be bent backward are inserted into the female terminal portions 211 that are stacked thereon and have the same configuration (see, for example, Japanese Unexamined Patent Publication No. 2001-307816).
The male terminal portions 212 are bent 180 degrees in the front of the press-fit joint connector having a one-stage parallel shape, and, as shown in FIG. 2B, a joint connector 200 is stacked on another joint connector 200 while being slid on the other joint connector 200, which lies underneath, whereby the terminals in the joint connector 200 having a vertically one-stage parallel shape are electrically connected. Although connector differing in their terminal configurations, this connector basically has a similar connection principle to that of the first prior-art joint connector 100, which was introduced first.
It should be noted that this case requires an operation in which the terminal joint portions (male terminal portions) are bent with two manufacturing steps after the terminals connected to electric wires are inserted into a housing.
Another prior-art joint connector, which is a third joint connector is provided with, as shown in FIGS. 4 and 5, a terminal 310 having on one end an electric wire-crimped portion 311, and on the other end a press-fit blade 312 in both the terminals' juxtaposed direction and the terminal housings' stacking direction. Then, the terminals 310 are inserted into a joint connector housing 300 having a one-stage parallel-shape, and after the connector housing 300 is stacked on another one and electric wires are wired in desired paths passing through the terminal press-fit portions, an electric wire supporting member is assembled with the connector housing 300. This produces a configuration in which predetermined press-fit terminals are conductively connected to each other through electric wires 320, 330, . . . etc. (see, for example, Japanese Unexamined Patent Publication No. 2001-229989).
In this case, connection can be made with a certain freedom with respect to the housings' stacking direction or the juxtaposed direction, but the electric wires 320, 330, . . . etc. need to be wired correspondingly.
The problems to be solved in the above-described first prior art are as follows.
The first prior-art joint connector 100, which was described first, has a special connection structure between its terminals, and therefore, the terminals that are necessary to be connected in the stacking direction (vertical direction) require a step of standing the male terminal portion 111 upwardly after inserting the terminals. In addition, because a terminal-linking portion is provided to make a connection in the direction of terminals' juxtaposed (lateral direction), it is necessary to cut off the terminal-linking portion for each wiring pattern by specifying the cut-off position. For this reason, in the use of the joint connector 100, cumbersome manufacturing steps such as bending-back of the terminals and cutting-off of the linking portion are required, which reduce efficiency in electric wire connecting operation by the joint connector.
In the case of the second prior-art joint connector 200, which was described next, as well as the case of the first prior-art joint connector 100, connection between the terminals is achieved by bending back portions of the terminals, and therefore, efficiency improvement in electric wire connecting operation cannot be made by the joint connector 200, as with the first prior-art joint connector 100.
Also, the third prior-art joint connector 300, which was described last, has a drawback in that it is provided with a press-fit blade for the stacking direction and a press-fit blade for the juxtaposed direction within one terminal and therefore the size of the terminal itself becomes large to a certain extent, accordingly increasing the size of the joint connector itself. Moreover, after the terminals 310 are inserted and the one-stage parallel-line-shaped connectors 300 are stacked, electric wires need to be wired and fixed into a desired circuit, which reduces efficiency in the connection operation for the joint connector 300.
Apart from these problems, the first prior-art joint connector 100 and the second prior-art joint connector 200 in particular have a drawback in that, because they have a structure in which one terminal has both a female terminal portion and a male terminal portion, the terminal itself has a complex configuration, which requires a complex molding in manufacturing the terminal, and quality control for the terminals becomes difficult.
Furthermore, since both of the male terminal portion and the female terminal portion are manufactured from one sheet of metal plate, the electrical resistance is high in the male-female contacts or the like and accordingly heat generation becomes great due to the requirement for types of material and thickness that matches the spring characteristics of the female terminal portion (for example, brass having a thickness of 0.25 mm) Therefore, a limitation in use arises in that a sufficiently large current cannot pass.
Next, a second prior art and its problems to be solved are discussed below.
A fourth prior-art joint connector, which relates to the second prior art, comprises an inserting-side connector portion and a receiving-side connector portion in which the inserting-side connector portion is inserted, and the inserting-side connector portion is guided by the receiving-side connector portion while being inserted so that the inserting-side connector portion and the receiving-side connector portion are fitted and connected with each other. The inserting-side connector portion is provided with a plurality of connector housings in which a plurality of terminal-accommodating compartments are juxtaposed in a lateral direction for accommodating connecting terminals, and a connector housing-locking means having an interlocking recess portion provided on the connector housing and an interlocking protrusion portion interlocked therewith, for stacking and combining the connector housings into a plurality of stages. The receiving-side connector portion is provided with a connector case having an inserting-side connector portion-receiving compartment for receiving and holding the inserting-side connector portion, and a circuit-forming unit mounted to the connector case and having a plurality of connection pins protruding in the inserting-side connector receiving compartment so as to be connected to the connecting terminals of the inserting-side connector portion (see Japanese Unexamined Patent Publication No. 2001-39239).
The problems to be solved in the above-described second prior art are as follows.
In the fourth prior-art joint connector, the inserting-side connector portion is normally configured by stacking a plurality of connector housings into a plurality of stages, and thereafter tightly inserting the interlocking protrusion portion into the interlocking recess portion of the connector housing-locking means by way of press-fitting after to combine them. Thus, it has a rigid structure such that the connector housings do not shift relatively to each other even when an external force is applied to the inserting-side connector portion.
Accordingly, in fitting and connecting such an inserting-side connector portion into the inserting-side connector portion-receiving compartment of the receiving-side connector portion, it is desirable to insert and fit the inserting-side connector portion into the inserting-side connector portion-receiving compartment of the receiving-side connector portion in a proper posture such that the axis of the inserting-side connector portion and the axis of the receiving-side connector portion are aligned to be parallel to each other. However, in the work of fitting and connecting the connector, the inserting-side connector portion is often inserted into the receiving-side connector portion in an inclined state, and it is difficult to insert the inserting-side connector portion in a proper posture. Since the inserting-side connector portion has a rigid structure, its insertion accordingly requires a great force. In addition to this, there is a risk of causing poor electrical connection in the connector because the insertion might become impossible halfway or the connector housings or the connecting terminals might be deformed by an excessive force applied thereto.
Moreover, in many cases, the thickness of each of the connector housings does not become a uniform dimension since there is a dimensional tolerance. In particular, ii case of the minimum value within the dimensional tolerance, pitch between the connecting terminals when the connector housings which are stacked sometimes becomes smaller than a predetermined pitch, and thus does not match the pitch of the connection pins of the circuit-forming unit in the mating receiving-side connector portion. Thus, there is also a risk of causing poor electrical connection in the connector since the connection pins of the receiving-side connector portion cannot be properly inserted into the connecting terminals of the inserting-side connector portion when inserting the inserting-side connector portion into the receiving-side connector portion.
Next, a third prior art and its problems to be solved are discussed below.
A fifth prior-art joint connector, which relates to the third prior art, is provided with: an inserting-side connector portion (stacked connector) in which connector housings, each having a plurality of terminal-accommodating compartments juxtaposed in a single layer for accommodating female terminals, are stacked into a plurality of stages and are combined by a connector-coupling means; and a receiving-side connector portion (electrical connection box) having a connector case (upper case) for accommodating the inserting-side connector portion inserted from one opening thereof, and a plurality of male terminals protruding in the connector case and connected to the female terminals of the connector housing in the inserting-side connector portion (see Japanese Unexamined Patent Publication No. 2001-39239).
Meanwhile, FIG. 6 shows an inserting-side connector portion 601 provided with connector housings 603, each having a plurality of terminal-accommodating compartments 602 juxtaposed in a single layer for accommodating female terminals (not shown), are stacked into three stages (see FIG. 6(A)), and these connector housings 603 are each combined by engaging an engagement recess portion 605 with an engaging protruding portion 606 of a connector-coupling means 604 (see FIG. 6(B)). In addition, an upper face of a cover 607 attached above the connector housing 603 stacked in the uppermost stage of the inserting-side connector portion 601 is provided with a locking arm 609 of a connector-locking means 608 for locking the inserting-side connector portion 601 and the receiving-side connector portion with each other when the inserting-side connector portion 601 is inserted into the receiving-side connector portion (not shown). On the upper face of the locking arm, an engaging protrusion 610 is protruded so that it engages with the engagement recess portion (not shown) provided on the upper wall of the connector case in the receiving-side connector portion. Reference character W denotes electric wires constituting a wire harness, and their terminals are connected to the female terminals accommodated in the terminal-accommodating compartments 602 of the connector housings 603 (see Japanese Unexamined Utility Model Publication No. 5-65073).
The problems to be solved in the above-described third prior art are as follows.
In the fifth prior-art joint connector, the connector-locking means 608 for locking the inserting-side connector portion 601 and the receiving-side connector portion with each other is provided at a location in the uppermost end side so that it locks the uppermost portion of the inserting-side connector portion and the uppermost portion of the connector case in the receiving-side connector portion.
Meanwhile, in the connector-coupling means 604 used for combining the connector housings 603, backlash (play gap or clearance) is not easily caused between the engagement recess portion 605 and the engaging protruding portion 606 since the engaging force in the direction of stacking the connector housings 603 is large; however, backlash is easily caused between the engagement recess portion 605 and the engaging protruding portion 606 since the engaging force in the direction along the surfaces of the connector housings 603, that is, in the direction in which the connector housings 603 are pulled out of the receiving-side connector portion is smaller than that in the stacking direction.
Accordingly, if a tensile force is applied to the electric wires W in such a manner as to pull out the connector housings 603 from the mating receiving-side connector portion, the backlash is accumulated more as the number of stacked stages of the connector housings 603 increases, and the connector housing 603 located in the lower shifts in the direction in which it is pulled out of the receiving-side connector portion. As a result, the connector housings 603 may be lifted and loosened, and the fitting between the female terminals of the inserting-side connector portion-side and the male terminals of the receiving-side connector portion-side can become insufficient. This degrades the connection state between both connector portions, and thus, there is a risk of degrading performance and reliability of the joint connector.
Next, a fourth prior art and its problems to be solved are discussed below.
A sixth prior-art joint connector in this prior art is generally provided with: a connection case in which an external connector for accommodating a plurality of female terminals is inserted; and a circuit-forming unit mounted to a base wall of the connection case and having a plurality of male terminals protruding in the connection case through a plurality of male terminal piercing holes formed in the base wall and a holder composed of a circuit board for supporting the male terminals. The male terminals of the circuit-forming unit are inserted into the female terminals of the external connector inserted in the connection case, whereby the joint connector is connected to the external connector (see Japanese Unexamined Patent Publication No. 2001-39239).
The problems to be solved in the above-described fourth prior art are as follows.
The joint connector of this type, used for wire harnesses, has had an increasing number of terminals in recent years, and the number of male terminals in the circuit-forming unit also tends to increase. As the number of male terminals increases, variations occur in dimensions and assembling accuracy of male terminals in the circuit-forming unit. This causes difficulty in smoothly passing these male terminals through male terminal piercing holes formed in the base wall of the connection case, making troubles in manufacturing (assembling) of the joint connector. In addition to this, there is a risk of degrading performance and quality of the joint connector when passing male terminals through male terminal piercing holes, as the male terminals may be deformed or damaged. For these reasons, the male terminal piercing holes formed in the base wall of the connection case are usually formed to have a bore diameter larger than the outer diameter of the male terminals with some margin so that the male terminals of the circuit-forming unit smoothly pass through the male terminal piercing holes.
When the bore diameter of the male terminal piercing holes is thus allowed to have some margin, it becomes easy to mount the circuit-forming unit to the base wall of the connection case. Nevertheless, this increases the clearance (gap) between the male terminals and the male terminal piercing holes, making it difficult to accurately position the circuit-forming unit against the base wall of the connection case. As a result, when mounting the circuit-forming unit to the base wall, the male terminals protruding in the connection case easily dislocate from predetermined locations, causing difficulty in aligning the male terminals and the female terminals when inserting the external connector into the joint connector; this may produce contact failures between both terminals.
In order to solve such a problem, a joint connector as shown in FIG. 7 is suggested and used. This joint connector is, as in the above-described connection box, provided with: a connection case 702 in which an external connector 701 for accommodating a plurality of female terminals is inserted; and a circuit-forming unit 705 mounted to a base wall 703 of the connection case 702, and having a plurality of male terminals 706 protruding in the connection case 702 through a plurality of male terminal piercing holes 704 formed in the base wall 703 and a holder 707 composed of a circuit board for supporting the male terminals. The male terminals 706 of the circuit-forming unit 705 are inserted into the female terminals of the external connector 701 inserted in the connection case 702, whereby the joint connector is connected to the external connector 701. In this configuration, a positioning protrusion 708 is protruded in the central area of the base wall 703 of the connection case 702, and in the holder 707 of the circuit-forming unit 705, a positioning hole 709 is formed, into which the positioning protrusion 708 is inserted with a small clearance so as to be attached and fitted thereto. Thus, when mounting the circuit-forming unit 705 to the base wall 703 of the connection case 702, the positioning protrusion 708 of the base wall 703 side is attached and fitted to the positioning hole 709 of the circuit-forming unit 705 side, whereby the circuit-forming unit is positioned so that the male terminals 706 protruding in the connection case 702 are held in predetermined locations without being dislocated.
In the seventh prior-art joint connector of this type, the positioning protrusion 708 is attached and fitted to the positioning hole 709 with no clearance, and therefore, when mounting the circuit-forming unit 705 to the base wall 703 of the connection case 702, the circuit-forming unit can be accurately positioned. However, it is necessary to provide a space for providing the positioning protrusion 708 on the base wall 703 of the connection case 702 in a protruding manner, and a space for forming the positioning hole 709 in the holder 707 of the circuit-forming unit 705 exclusively. In addition, the shape of the circuit pattern of the holder 707 needs to be wired in such a manner that it extends outwardly to get around the positioning hole 709. As a result, a problem arises in that the shapes of the connection case 702 and the circuit-forming unit 705 become large, increasing the size of the joint connector; moreover, since the shapes of the connection case 702 and the circuit-forming unit 705 becomes large and the positioning protrusion 708 is provided in a protruding manner, the material cost increases, and accordingly the cost of the connector increases.
Next, a fifth prior art and its problems to be solved are discussed below.
An eighth prior-art joint connector is discussed as a joint connector related to a fifth prior art. The eighth prior-art joint connector is provided with: a plurality of connector housings each having a plurality of terminal-accommodating compartments juxtaposed therein for accommodating connecting terminals connected to electric wires constituting a wire harness or the like by crimping or the like; a connector housing-locking means composed of an interlocking recess portion and an interlocking protrusion portion for stacking and combining the connector housings into a plurality of stages, provided respectively at a front and a back of each of the connector housings on both side portions thereof, so that an interlocking recess portion or an interlocking protrusion portion provided on one of the connector housings is engaged with an interlocking protrusion portion or an interlocking recess portion provided on another one of the connector housings that is stacked thereon; and an interlocking protrusion protruding on the other stacked connector housing so as to engage with the connecting terminal accommodated in the terminal-accommodating compartment of the one of the connector housings, for preventing disengagement of the connecting terminal and detecting an incomplete insertion.
In the connector housing-locking means that is provided at the front of the connector housing on both side portions thereof, its interlocking recess portion is formed of a recessed groove opened upwardly above the connector housing, and having an extended-diameter stepped portion in its lower inner bottom portion, whereas its interlocking protrusion portion is a linear interlocking piece protruding downwardly below the connector housing and having a claw for engaging with the extended-diameter stepped portion at its fore-end.
In the connector housing-locking means that is provided at the rear of the connector housing on both side portions thereof, as opposed to the connector housing-locking means provided at the front, the interlocking recess portion formed of a recessed groove opened downwardly below the connector housing and having an extended-diameter stepped portion having its upper inner bottom portion, whereas the interlocking protrusion portion is formed of a linear interlocking piece protruding upwardly above the connector housing and having a claw for engaging with the extended-diameter stepped portion of the interlocking recess portion at its fore-end (see Japanese Unexamined Patent Publication No. 2002-246127).
The problems to be solved in the above-described fifth prior art are as follows.
The eighth prior-art joint connector is generally configured to be assembled by stacking the connector housings into a plurality of stages and combing them by the connector housing-locking means in a state where the connecting terminals are accommodated in the terminal-accommodating compartments of the connector housings. Also, when the connector housings are stacked, by the configuration of the connector housing-locking means, the connector housings are stacked by shifting and overlaying them in a direction perpendicular to the inserting direction of the connecting terminals. If the connecting terminals are accommodated in the terminal-accommodating compartments of the connector housings in an incompletely inserted state, the interlocking protrusion protruding on a connector housing to be stacked hits the wall or the like of the connecting terminal and does not engage with the engaging portion. This can be utilized to detect an incompletely inserted state of the connecting terminals.
The connector housings are generally formed by plastic molding and therefore have the advantages of being lightweight, inexpensive, and easy to manufacture; however, their strength is not sufficient, so they can be easily deformed by an applied external force. For this reason, even if such inconvenience arises that the connecting terminals are accommodated in the terminal-accommodating compartments in an incompletely inserted state and the interlocking protrusion does not engage with the connecting terminals, the interlocking protrusion tends to slide aside by the partial deformation of the terminal-accommodating compartments, which is the same condition as if the interlocking protrusion engages with the connecting terminals. Thus, a proper detection for the incomplete insertion of the connecting terminals becomes impracticable, and there is a risk of combining the stacked connector housings in the condition where the connecting terminals are accommodated in terminal-accommodating compartments in an incompletely inserted state. This causes a problem of degrading performance and reliability of the connector.
In order to resolve such a problem, it is conceivable that by increasing the wall thickness of the terminal-accommodating compartment in the connector housing and thereby increasing its mechanical strength, deformation of the connector housings in stacking the connector housings is prevented and an incompletely inserted state of the connecting terminals is reliably detected to prevent combining a connector housing with a connecting terminal being in an incompletely inserted state. Nevertheless, this causes the connector housing to have a larger outer dimension, and therefore, as the number of stacked stages of connector housings increases, the size of the joint connector accordingly becomes larger, causing inconvenience in assembling it in various equipment or the like, which is another problem.